1. Field of the Invention
The present invention relates to antenna technology and more particularly, to a printed circuit board type asymmetrical dipole antenna that effectively broadens the operating bandwidth.
2. Description of the Related Art
A simple mono-pole antenna has an operating bandwidth about 10%, which is relatively narrower when compared to regular international communication standards. Further, a mono-pole antenna usually needs to use the antenna-carrying circuit board or the ground-contact area of the antenna-carrying mechanism as a negative pole for energy radiation, and the radiation pattern is determined subject to the antenna-carrying mechanism. When the size of the antenna-carrying mechanism is greater than ¼ wavelength (λ), the radiation current will undergo a phase change to destructively interfere with magnetic waves in space, leading to communication dead angle.
Further, a conventional dipole antenna or loop antenna commonly has a predetermined size of radiator and a parallel feeding-line structure connected to the radiator for the feeding of signals. The bandwidth utilization of a conventional dipole antenna or loop antenna is simply about 8˜12%. Due to narrow operating bandwidth, conventional dipole antennas and loop antennas cannot satisfy the requirements for wireless application.